The present invention pertains to laminates which are waterproof, blood-proof and virus-proof, yet have a very high moisture vapor transmission. These laminates are suitable for use in protective apparel for adverse climate conditions (i.e. rainwear, skiwear and the like) as well as for hospital or medical garments which must withstand adverse washing and sterilization conditions.
Recent studies have shown the risk to healthcare workers of viral disease transmission from infected patients to be extremely high. In 234 operations ranging from general to cardiothoracic surgery and including six other surgical specialties, 50 percent resulted in at least one person becoming contaminated. Routes of contamination were through cuts, sticks and splashes.
The Occupational Safety & Health Administration's (OSHA) final regulation regarding occupational exposure to bloodborne pathogens appeared in the Federal Register on Dec. 6, 1991. This final regulation is extremely far reaching in its attempt to offer healthcare workers a realistic approach in addressing means for minimizing risk in the present environment, in which the threat of both Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) exposure are of great concern. The regulation requires that gowns and fabrics which are now available must offer sufficient resistance to fluid penetration and virus penetration and must be washable and sterilizable a minimum of 100 times at 275 degrees Fahrenheit for 5 minutes to reduce the cost of health care.
Any employee who may be exposed to human bodily fluids which may be infectious is covered by the OSHA regulation. Thus the entire healthcare sector is covered by the OSHA standard, including hospitals, outpatient facilities, medical and dental laboratories, physician's offices, nursing homes, research laboratories, linen services, and handlers of regulated waste. Outside the healthcare community, the regulation also covers the areas of law enforcement, fire and rescue organizations and correctional institutions. A total of 5.6 million workers are estimated to be covered by this regulation, 78 percent of which are employed in the healthcare profession.
Currently, the most commonly used waterproof, but breathable, laminated fabric is Gore-tex II.RTM. produced by W. L. Gore Associates Inc. A microporous poly-tetrafluoroethylene (PTFE) laminate material is riddled with billions of tiny pores too small for water droplets to penetrate, but large enough for water vapor to escape. This microporous PTFE is laminated to the inside of a wide variety of fabrics. To achieve a lamination without interfering with breathability, millions of tiny dots of adhesive are used to laminate the PTFE membrane onto fabric (since the PTFE membrane cannot be successfully laminated directly onto the fabric). U.S. Pat. No. 4,194,041 to Gore et al. discloses using at least one layer of a hydrophilic material, such as Hypol.RTM. (by W. R. Grace & Co.) to coat the PTFE membrane to prevent the transport of surface active agents and contaminating substances, such as those found in perspiration, detergent and soap, and to prevent abrasion, which can affect the ability of the PTFE membrane to prevent water penetration.
This fabric has several drawbacks, including its cost. The PTFE membrane has no elastic recovery. In addition, the PTFE membrane is sensitive to scratching (hence its use as a "sandwich" laminate or as an insert in high performance garments). Finally, such microporous membranes are often less effective than desired as they have too many oversized pores.